- #1
Tanishq Nandan
- 122
- 5
Homework Statement
A metal strip 8.5cm long,0.65 cm wide,0.76 mm thick moves with constant velocity v through a uniform magnetic field B=0.2mT directed perpendicular to the strip,as shown in figure.A potential difference of 3.9 microV is measured between points x and y across the strip.Calculate the speed v.
Homework Equations
●E=V/d,
where d is width of strip,V is potential difference(Hall potential) across that width(3.9microV,here) and E is the electric field inside that strip.
●n=Bi/Vet,
where
n=no of conduction electrons per unit volume of strip
B=magnitude of magnetic field
i=current flowing through that strip
V=Hall potential,described in previous formula
e=charge on electron
t=thickness of strip(0.76 mm here)
●Basic theory of Hall effect:On applying a magnetic field perpendicular to the strip,some electrons get accumulated at one side of the strip due to the magnetic force acting on them,which after a while causes an electric field to be produced inside the strip across it's width,which opposes and finally cancels the effect of the magnetic field,thus allowing current(which is nothing but charged particles) to flow through the strip unhindered.
The Attempt at a Solution
I don't understand how the entire strip is moving.
Hall effect is about the two fields (electric and magnetic) cancelling out each other.but how can the entire strip move with a constant velocity.
Things i feel we may need to do:
Find n (2nd formula above) to get total no of conduction electrons,and find total force due to each of them due to the magnetic as well as electric field,but then there are several problems,
1.we don't know current (i in the formula)
2.what to do with the electrons which are accumulated on eithe side on the strip,responsible for the electric field being created,is the force on them just magnetic or electric as well??
So, I am not able to grasp what exactly happens to make the entire strip move.
(there is also the formula of F=BIL but I didn't mention it because again,we don't know current)